- Autor
- Zelenka, Jan
- Pirker, Gerhard
- Kiesling, Constantin
- Eder, Lukas
- Winter, Hubert
- Meyer, Georg
- Wimmer, Andreas
- TitelIgnition Concepts for Large-Bore Gas Engines – A Comparison of Spark, Laser and Diesel Pilot Ignition
- Datei
- DOI10.3217/rcdc1-ry416
- Erscheinungsjahr2019
- Seiten1-17
- LicenceCC BY-ND 4.0
- Konferenz Name29th CIMAC World Congress on Internal Combustion Engines
- Konferenz OrtVancouver
- Konferenz StaatCanada
- Download Statistik998
- Peer ReviewJa
- AbstractThe majority of modern large bore gas engines are operated using a lean combustion concept to comply with existing NOx emission limits without exhaust aftertreatment. Prospective emission regulations call for significantly lower NOx emissions. Engine internal measures to achieve this goal include further enleanment of the cylinder charge and high EGR ratios. Exhaust gas aftertreatment increases the size of the engine system; greater power output compensates for the demand for more space. High specific engine power, very lean mixtures or high EGR ratios pose high demands to the ignition of the mixture. This paper compares the potentials of three different ignition concepts (spark ignition, laser ignition and diesel pilot ignition) applied to large engines. First, the basics of the ignition concepts are compared by theoretical considerations with respect to available ignition energy and temperature, introduced turbulence and stochastic influences. Measurements from the single cylinder research engine are used to evaluate the influence of the ignition source based on the achievable efficiency and emissions values. Furthermore, the impact on cycle-to-cycle variations is assessed. When the ignition systems are compared, the boundary conditions of the cases under investigation are set to identical values whenever possible. Finally, the measurement results are further analyzed based on 3D CFD simulation. Highly sophisticated simulation models already validated in prior research are applied in order to simulate the processes relevant to ignition, flame kernel development and combustion. For the modeling of spark ignition, a spherical ignition model is used providing a defined initial flame kernel at the spark plug over the duration of energy deposit by the ignition system. Laser ignition is considered by an ignition model that generates an infant flame kernel represented by a sphere inside the combustion chamber. The size of the sphere is provided by a detailed plasma model for the blast wave resulting from the instantaneous energy release by the focused laser beam. Finally, for diesel pilot ignition a detailed reaction mechanism is used to obtain the relevant ignition delay values. The models are used in connection with 3D CFD simulation, which also provides the required turbulence values. The effect of each ignition concept on the induced energy to the cylinder charge as well as on the evolution of the initial flame front is investigated.
[845.82 KB]